Method of heat-treating sheet and tin-plate bars



T. V. ALLIS. METHOD 0F HEM TREATING SHEET AND TIN PLATE BARS. APPLICATIQN FILED 1AN.29,1918.

1,367,000, lleamlted Feb. 1, 1921.

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T. V. ALLIS. METHOD 0F HEAT TREATING SHEET AND TIN PLATE BARS.

A P P L I C A T I D T F l L E D l A M 2 9 l 9 l 8; T

1,367,000. Patented Feb. 1, 1921.

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AHORA/Ex l Tl V. ALLIS. METHOD 0F HEAT TREATTNG SHEET AND TIN PLATE BARS. APPucATloN- FILED 1m29, 191B.

1,367,000. Patented Feb. 1,1921.

SHEET 4- 4 SHEETS- FIGS' 26 VV Y A L UNITED STATES PATENT` OFFICE.`

THOMAS V. ALLIS, 0F PITTSBURGH, PENNSYLVANIA; HANNORA E. ALLIS ADMINIS- TRATRIX OF SAID TIIOINLAS V. ALLIS, DECEl-ISED.

METHOD OF HEAT-TREATING SHEET AND TIN-PLATE BARS.

Specification of Letters Patent.

Patented Feb. 1, 1921.

Application filed January 29, 1918. Serial No. 214,270.

To all whom t 'may conce/m.'

y Be it known that I, THOMAS V. ALLIs, a citizen of the United States of America, residing at Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Methodsof Heat-Treating Sheet and Tin-Plate Bars, of which the following is a. specification.

The present invention relates to the art of heat treating sheet and tinplate bars, and is an improvement in, method whereby oXi- (lation of the surface of the bars is practically eliminated, and consequent scale prevented. A further object of my invention is to produce bars of one and the same general caloric condition, so that theprocess of rolling the bars into sheets is thereby much facilitated, and the waste of material minimized as will be explained hereinafter.

In the accompanying drawings I have illustrated the use of my invention in con' nection with two types of pair furnaces, both of which are adapted to carry out `my invention, as this specification will set forth fully as the description proceeds.

Figure 1 is a horizontal section of a pair furnace taken on line 1-l of Fig. 3.

Fig. 2 is a partial vertical section of Fig. 1 on line 2-2 of the same.

Fig. 3 is a vertical centralsection taken on line SH3 of Fig. 1.

Fig. 4t is an end view of a piling rack or gage. h

Fig. 5 is a side View of Fig. 4.

Fig. 6 is a horizontal section of a pair furnace taken on line 6-6 of Fig. 9.

Fig. 7 is a partial vertical section of the same taken on line -7 of Fig. 6. y

Fig. 8 is a vertical section taken on e--s of Fig. e.

Fig. 9 is a central vertical section on line 9-9 of Fig. 6.

Fig. 10 is an end view of a modified form of piling `rack or gage.

Fig. 11 is a side view of Fig. 10.

Fig. 12 isan enlarged detail vertical sec` tion on line 12--12 of Fig. 13, showing the movable fulcrum and associated parts shown in Fig. 9.

Fig. 13 is a plan view of Fig. 12 showing the method of attaching the movable fulcrum to the front of a furnace.

It willbe seen from the drawings that Figs. 1 to 5 inclusive show one` type. of pair line M furnace construction, while Figs. 6 to 9 inclusive show a second and different type of pair furnace.

The use of my invention in connection with the first mentioned type of furnace shown in Figs. 1 to 5 inclusive, will be first explained. The numeral 1 indicates a pair furnace, having a heating chamber 2, a bridge wall 3, and a hearth l1. The furnace 1 is also provided with down-take flues 5, 6, arched connecting passages 7, 8, 9 beneath'the hearth 4, and a stack flue 10.

A series of interengaging small doors 11, 12 close the charging opening 13 for a pur pose stated below. The burning gases enter the heating chamber 2 over the bridge wall 3, from the iireboxes (not shown) in the usual way, thence pass tothe downtake flues 5, 6 and by means of the passages 7, 8, 9 escape toand through the stack flue 10. In the heating chamber 2 I have provided two hearth skid castings 11i, 15, which are adapted to Support the sheet and tinplate bars 16 in an inclined position as shown, resting on one edge and a side. 17 and 18 represent two specially constructed piling racks each having a vertically disposed member 19, and two `oppositely disposed members 20, 21. This special rack 1s clearly illustrated in Figs. 4 and 5, from which it is seen in connection with Figs. 1 and 2 that bars 22 can be piled regularly and evenly upon each other with their longitudinal and vertical edges in perfect alinement. The in clined members 20, 21 enable the bars 22 to gage themselves against the central vertical g member 19, gravity readily assisting them totheir proper alined position as indicated in the Fig. 2 of the drawings. 63 indicates a modified form of piling `rack designed to take a central position within the furnace similar to thepiling rack 17, and adapted to receive the bars 22 as indicated by the dotted lines in Fig. 10. In using this type of piling rack 63 a considerably greater number of bars arebrought together inasingle pile while receiving the soaking treatment than' when the rack 17 is used, thereby facilitating the distribution of heat throughout the mass and producing bars practically identical as to temperature condition. It is readily appreciated that the larger the pile and number of bars associated in one mass, the more evenly the heat will be distributed throughout said mass.

The bars to be treated vary somewhat in length, but it is seen that the hearth skids 14,

211 forgaging the bars in similar fashion to those on the piling racksV 17, 18.

In carrying out my invention in this type of furnace l proceed as follows. The bars are charged through the small doors 11, 12, etc., which expose only a small portion of the opening 13 at any one time, so as not to disturb the heat conditions within the heating chamber more than is absolutely necessary, the idea being to hold the soaking temperature of the bars within the said chamber at a constant point as far as practicable'. The bars charged are placed in piles illustrated by 16 and 23 on the hearth skids 14, 15, twofpairs of bars usually being associated and handled as a unit when lplacing them on the skids. After the bars are partially heated on the hearth skids they are removed one or more pairs at a time, by

Vlifting them manually with a pair of tongs inserted in the longitudinal grooves 25 of the hearth skids, and placed on the piling racks or gages 17 and 1S,V as shown in Fig. 2.l InV forming the piles on the said racks 17, 18 an outer pile of bars 16 (i. c. a pile nearer the doors 11, 12,ctc.), and an inner pile. 23 c. a pile nearer the fire wall 3) are successively superimposed upon each other in alternate relation on the piling racks. VThe reason for Vthis procedure is that the inner piles of bars 23 positioned on the'vskidsin the interior of the heating cha n- 'ber 2 are exposed to a more intense heat than the outer piles 16, and when they are piled alternately on the racks, the temperature of the whole mass of bars is equalized.

-The hotter bars radiate heat to those -of lower temperature, and the latter readily absorb the heat so radiated according to a. well understood physical principle, and thus a mass of bars of a uniform caloric condition Vis produced. Further it is seen that the even piling of the bars both on the hearth skids 14, 15 and on the piling racks 17, 18 with their vertical and 'longitudinal edges in practically perfectfalinement prevents oxidation of the surface of the bars, and the undesirable scale is reduced to a negligible minimum.

Attention is directed to the fact that when the bars arehandled in the heat-ing chamloer the angle 'of inclination at which the same are held is comparatively flat and such as will prevent the fan-tailing of the bars. It is seen .that in lifting a pile of bars such as 16 with the tongsusually employed, if the angle at which the bars are held is much greater than thatdes'cribed each bar willslide around partially on the face of its associate, and a portion of the surface of the bars thus become exposed to the process of oxidation and objcctionabh` scale thereby produced. lt will be noted that the piling racks l?, 18 are placed in thc center of thc heating` chamber 2 in this type of furnace, as the temperature is found to be almost con stant at this point, and not subject to thc wall drafts usually found at or near the sides of the furnace hearth` which are duc to the influence of the brick walls. their radiation, and other disturbing causes.

After the bars have been soaked su l'- iiciently on the piling racks 1T. 1S they are withdrawn through thc small doors 1l. l2. etc., and reduced by rolling;` to shccts of the proper gage.

In connection with the importance of producing uniformly heated bars, it may be stated that bars are usually rolled down into sheets in pairsf that is two bars arc associated and rolled as a laminated unit. and said bars are made of a certain sizcc which will just produce after rolling` and doubling, sheets of a predetermined length with a small amount of material which over-runs7 the desired length. The por tion of the sheets which makes this excess is sheared off as waste material. The gage 0r thickness of the sheets is also determined by their rolled length. and it is readily appreciated that when one pair of bars is more highly heated than thc ayerage the material being softeK as a conscquence, produces sheets of a greater length than the size desired, and the amount ol waste7 material is thereby unich increased. Fu iorc when one pair of bars is more highly heated than another, the adjustment of the rolls of the mill has to be constantly attended to due to the variation in thickness between the more highly heated and cooler pairs of bars. lVhen the bars are ally of practically a uniform temperature as is accomplished by my invention, this practical inconvenience in rolling is entirely climinated.

Viith reference to the type of furnace indicated by Figs. G to 9 of the drawings inclusive, 2G indicates a pair furnace haring a tire box chamber27, a bridge wall 2S. a heating chamber 29 and a hearth 30. The usual down-take tlues 31, 32 are shown. and the arched connecting passages 33, IH. 35 leading to the stack Hue 36 are also shown in the drawings. The burning gases cuter the heating chamber 29 over the bridge wall 2S. pass over the hearth 30, enter the dowirtakc iiucs 3l, 32 and escape to the stack flue :lli by means of the arched passa 33, 3l, 35. The heating chamber 29 is provided with one or more hearth skids 37. which can be formed into two separate castings by dividing same along the dotted line 38, or can be made of a single casting as desired. The hearth skids 37 have inclined supporting surfaces 39, 40 on which are placed the bars 41 to be heated. On each side of the interior of the heating chamber 29 are a series of upright `projecting gage castings 42, 43, 44, 45 which are inset as shown in the walls 46, 47 0f the furnace. Adjacent to the upright castings 42, 43, etc. are a series of transverse castings 48, 49, etc. which are inset in the hearth in an inclined position as shown in the F ig. 8 of the drawings. The castings 48 form a lap joint with the vertical castings 42, at 50, for convenience in construction, while the castings 43, 44, 45 form butt7 joints at 51 with the transverse castings 49 for the same purpose.

I have provided a movable fulcrum 52, having two arms 53, aivoted at 54 in divided jaw castings 55, the latter being carried by the fascia.- plates 56 of the front of the furnace, and the use of said movable fulcrum will be described below.

In practising my method of heat treatment of sheet and tin plate bars in this second type of furnace, the bars are charged through the doors 57, and placed on the hearth skids 37, Where they are partially heated. They are then placed on the inclined castings 48, 49 where they at once range themselves against the upright gage castings 42 to 45 inclusive, in vertical and longitudinal alinement. After a period of soaking the bars are removed through the doors 57 and rolled down into sheets of the desired size. i

When the bars 41 are stacked at the sides of the furnace heating chamber 29 as at 59, it is readily understood the heater7 handling the bars by means of the tongs usually employed, rests the said tongs on the fore plate 58 of the furnace as a fulcrum. Vhen the piles of bars 59 are higher than usual it will be apparent that a slightly elevated fulcrurn is necessary for convenience in handling the said bars, in which event the mov able fulcrum 52 (which ordinarily is in the position shown dotted at 60), is swung about the pivot point 54 into the working position shown in Figs. 7 and 9 in full lines at 6l..

It is noted that a second hearth skid similar to 37 can be placed lupon the hearth 3l) at point marked 62, and parallel with said skid 37, thus forming a second point of support for bars of various lengths. The advantages stated with reference to the method as used in connection with the first' type of furnace apply equally to the second type of furnace with the exception that the bars being csoa red in the latter are more subject to wall drafts before explained in this specification.

From which it is seen that I have provided a very eiiicient method of heat treatment for sheet and tin plate bars, whereby bars of a uniform temperature are produced, having a negligible amount of Scale surface.

l. The method of heat-treating sheet and .tinplate bars to uniformly soften and minimize their oxidation, which consists in initially heating them in primary piles on a furnace hearth, transferring and arranging said piles against a gage in the center of the hearth to form secondary piles, and then completing the heat-treatment while the bars are in the last described position.

2. The method of heat-treating sheet and tinplate bars, which consists in initially heating them in primary piles, transferring and re-arranging said piles to form secondary piles composed of alternate layers of bars taken from primary piles of varying eomparative temperatures, and completing the heat-treatment while the bars are thus disposed upon the furnace hearth.

3. The method of heat-treating sheet and tin-plate bars, which consists 1n initially heating them in primary piles, transferring and re-arranging said piles against a gage in the center of the furnace to form secondary piles composed of alternate layers of bars of diiferent comparative temperatures, and then completing the heat-treatment while the bars remain 1n the secondary piles aforesaid.

4. rI"he method ofheat-treating sheet and tinplate bars, which consists in initially heating them in primary piles with the edges of the bars in substantial alinement; transferring and forming secondary piles by arranging bars of varying temperatures taken from prima-ry piles, in alternate layers with their edges in alinement; and then continuing the heat-treat1nent until all of the bars of the secondary piles are uniformly softened throughout.

In testimony whereof I affix my signature in. the presence of two witnesses.

'IH(.)MA S V. ALLIS.

Witnesses WILLIAM A. HIR'rLn, A. VVILsoN McCaNuLnss. 

